Stoking grate



kMay 26, 1936.

45 4f" 47% f- 71H 4Z 1 36 4f 1 G F. L. DUMONT STOKING GRATE Fi1ed Feb.21, 195s '2 sheets-shewV 2 INVENTO ATTORNEY Patented May 26, 1936 STTES4 Claims.

The present invention relates to improvements in stoking grates and inmethods of stoking fuel carried thereon. It has long been thedesideratum in this art to provide a stoking grate or so-calledmechanic-al stoker which will feed the solid fuel evenly and uniformlyfrom one end of the furnace grate to the other, without rendering thefuel bed of uneven thickness and producing uneven spots or holes whichinterfere with the lo combustion process, and without occasioning asubstantial loss of fuel through the grate.

In accordance with my present invention, I propose to feed the fuel bysuccessive thrust movements, a small portion thereof at a time, whereispreserved. Preferably, the feeding is accomplished by first moving asmall portion of the fuel at the remote or rear end of the furnacerearwardly, such movement being followed by a movement forward of thefuel increment immediately forward the fuel first moved, and thesemovements repeated in succession until the fuel nearest the front of thefurnace has been moved, whereupon the cycle is repeated, freshfuel beingadded preferably'at the front of the furnace. In this manner, eachportion of the fuel is moved easily as a space upon which it is to resthas been prepared for it by the fuel movement which preceded it. At thesame time the amount of fuel moved at any one time is insuflicient todisturb the thickness of the fuel bed substantially. In the prior art,so far as I am aware, this uniformity of movement could not'take placesince a large fraction of the fuel was moved at each stroke. One reasonfor this is that heretofore it has been impracticable to providesuicient mech- Y anism for accomplishing any such movement ascontemplated by the present invention because the space in the front ofthe furnace where such mechanism is disposed is necessarily limited.

The practice now common in stokers of various types is to use a singleoscillatory actuating shaft in front of and parallel with the front ofthe furnace for the purpose of imparting movement to the grate bars. Animportant object of my invention is to utilize this type of actuatingshaft by providing an improved electrical coupling between the shaft andthe connections to the individual grate bars by means of which thisshaft may be caused to actuate any one of the bars in any desiredsequence. My improved coupling also involves a timing device of specialconstruction'by means of which not only the 'sequence of operation ofthe grate bars may be determined but also the frequency of suchoperation in acby great uniformity of feed and of depth of fuel cordancewith a desired combustion rate. A further ob-ject of my invention is toprovide grate bars of uniform size and shape which may beinterchangeable with any other grate bar in the same furnace.

Other and more specific objects of my invention will be apparent as thedescription proceeds and the novel features of the invention will bepointed out in the appended claims.

lVIy invention will be best understood by reference to the followingdetailed description taken with the annexed drawings, in which Figure lis a view, partly in vertic-al section, of a side elevation of a stokinggrate to which a preferred embodiment of my invention has been applied;

Figure 2 is a side elevation of an individual grate bar;

Figure 3 is a view taken along the section 3 3 of Figure 2;

Figure 4 is a view, partly in vertical section, of my improved couplingdevice;

Figure 5 is a diagrammatic view showing the timing device and theelectrical connections between it and the coupling devices;

Figure 6 is a View of the timer showing the means for driving same;

Figure '7 is an edgewise view of the timer viewed from the bottom withrespect to Figure 6 but with the element 61', Figure 9, removed for-sakeof clearness;

Figure 8 shows the actuating shaft and coupling device with the lead-inwires in place; and

Figure 9 is a view taken on line 9 9 of Figure 7.

Referring to Figure 1, a stoking grate l0 is shown as composed ofindividual inclined grate bars Il, of the type shown in Figures 2 and 3,each of'which is provided with trunnions i3, I3 which rest in sockets ofsupporting plates of known type, not shown. E'ach grate bar is latticedalong the fuel supporting surface as indicated Vat l5, Figures 2 and 3,one vertical side I6 of the bar being longer than the opposite side andhaving a portion formed of cylindrical shape, the axis 0f which passesthrough the trunnions I3. The grate bar thus far described is of knowntype and per se forms no part of the present invention. As indicated inFigures l, 2 and 3, the bar is adapted to be rotated to the position ofthe third bar from the right in Figure 1, and by such movement advancethe fuel from one end of the grate tothe other. For moving the bars, -alever and link system is provided including a lever i9, one end of whichpreferably is of a shape fitting between the sides I6 and l1 of the barand which is attached thereto at a convenient portion thereof,preferably by bolting it, as by bolt 2l, to any one of a plurality ofreinforcing fins 22 which are formed at spaced intervals throughout thelength of the bar. A link 24 is pivotally attached at 25 to the oppositeend of each lever I9, such links 24 extending from the bars Il throughthe front plate 21 of the furnace where they are attached to theactuating means to be described A dumping section 28, pivoted at 29, isalso shown at the right of the series of bars II and also is connectedto the front of the furnace by means of link 36.

Suitably journaled at the front of the furnace (journal 3 l) is anactuating shaft 33, means being shown in the form of arm 34, link 34aand rotative disk 34h, Figure 1, for oscillating this shaft by an amountwhich will give the desired throw to the bars Il. Shaft 33 is connectedto each of the links or rods 24 by means of a coupling device denotedgenerally by 35 and forming a part of my present invention. Thisdevice', which is best shown in Figure 4, is pivotally connected to alink 24 through a pair of ears, one of which, 35, is seen in Figure 4.It is the function of each coupling device 35 to operatively join thelink 24 associated therewith to the shaft 33 at such times as may bedesired and which are predetermined in advance. To accomplish this Ihave provided the following mechanism: A key 31 is disposed within acollar 39 surrounding the shaft 33, such key being adapted to registerwithin a spline way or slot 39 formed within the shaft 33 and extendingpreferably continuously with the shaft. The collar 38 is bolted to theshell 46 of the coupling by means of suitable bolts (bolt 4|). Withinthe shell 46 of the coupling 35 is a solenoid winding 42 having a fixedcore 43 of soft iron and a movable core 44 also of this material. A pinof non-magnetic material 45 extends from the key 31 to the core 44through a bore in the core 43. The solenoid comprising the various partsmentioned is held within the shell without vibration, preferably bymeans of a spring Y 43 which causes the top of the winding 42 to press iagainst a collar 41 of the core 43 which in turn causes the latter to bepressed within a slight recess 48 within the collar 33. A suitable spaceis provided between the shell 49 and the collar 41 for the electricalcable 5 supplying current to the winding 42.

It is apparent from the foregoing that when the current is turned on themovable core 44 will be drawn upwardly and will press the pin and hencethe key 31 into the slot 39 upon registry therewith. This will cause thecoupling 35 to be pinned tothe shaft 33 and to be oscillated by it untilsuch time as the current is released and the key 31 is allowed to dropby gravity out of the slot 39. In operation it is desirable to have thecurrent on until after the bar l! has completed device by means of whichthe several coupling devices are actuated. Referring to Figure 5, acommutator is provided consistingof a conducting not shown, before thehandle is moved.

ring 56 and contact areas 51 of a number equal to the coupling devices.A rotatable switch arm 59 connects in sequence the contacts 51 with thering 56 whereby circuit is established from the source of E. M. F. 60through the solenoids of the 5 coupling devices 35. VThe switch arm 59is connected to shaft 6| which is driven in timed relation with theshaft 33 by a connection comprising an arm 62 on shaft 33, a link 63 anda lever 64 pivoted to shaft El and driving this shaft and 10 the contactarm 59 attached thereto through the pawl 64 and ratchet wheel 65 splinedto shaft 6l. The arrangement is such that depending upon the adjustmentof plate 61 the electric circuit through any given solenoid isestablished when 15 the slot 39 is directly over the key 31 and preferuably slightly before this event. Means are also provided for varying thespeed of rotation of the arm 59, and consequently the rate of fuel feed,by varying the effective throw of the pawl 34. For this purpose a plateE1 is rotatably mounted 0n shaft 6I and is held in position by a springpressed detent 61', Figure 9, in such a manner that it can be rotatedslightly by means of the handle 63, plate 61 having a portion cut awayfrom the periphery so as to permit the pawl to engage the ratchet wheelE5 while the non-cut portion prevents the pawl from engaging the ratchetwheel 65, such number of teeth skipped depending upon the position ofthe plate. In one extreme position a single throw of the pawl willadvance the ratchet wheel 65 by three or more teeth whereas in the otherextreme position, obtained by moving plate 61 by a handle 68, the pawlwill ride over all but one tooth on each forward movement. By means ofhandle 69 attached to shaft 6l it is also possible to move the arm 59manually so as to operate any grate bar desired. The manual operation ofhandle 59 should occur when the slot 39 and the shaft 33 40 (as revealedby the position of the coupling then in connection with the shaft) isaway from the vertical so as to obviate the connecting up of the bar 33with coupling devices intermediate the one in action and the one it isdesired to put into 45 action. Since the movement of the shaft 33 isvery slow, this operation is readily performed. Or, if desired, thecircuit involving the source of E. M. F. 6 may be broken by means of aswitch,

50 In the embodiment shown, the commutator 55 forms both the functionsof a distributor and a timer but obviously these functions may beperformed by a separateY timer and a separate distributor, as is wellknown in the art, if desired. 55 In operation, the shaft 33 isoscillated at such a speed that several oscillations will be required tomove the switch arm from one contact to another for the slowest fuelmovement desired. By regulating the position of the plate 61 from 60 theposition of slowest speed, less oscillation of the shaft 33 will berequired to move the switch arm from one contact to the other and hencethe frequency of operation of the grate bars will be increased. Whencontact is made by the switch 65 arm 59, the current will be on untilthe ratchet is again moved, an interval long enough to have the currenton throughout the upward movement 4of the coupling (Figure 1) and for ashort interval thereafter. It will be noted, however, that what- 70 everfrequency is used the time required for one complete movement of eachgrate bar is the same. From the foregoing it will be evident that I haveprovided coupling means between the main actuatingshaft 33 and the links24 which may 75 be actuated in any desired sequence and preferably so asto effect a progressive feed of the fuel by actuating successive gratebars starting with the one nearest the back of the furnace. By means ofthis progressive movement, tendency to disrupt the fire bed is reducedto a minimum. On the other hand, if for any reason .a portion of thefuel bed becomes overloaded or a portion becomes too thin, it ispossible to immediately remedy this situation by bringing into playthose grate bars in the region concerned. Or, should it be desirable tooperate any two or more of the grate bars together, -as for examplesuccessive bars, this can be effected by connecting to the samecommutator segment the solenoids of the grate bars whose simultaneousoperation is desired. It will further be seen that the utmostflexibility has been achieved, all with maintaining the same economy ofspace as has been obtained in the prior art where half of the grate barshave been operated .at one time. It is also apparent that I haveprovided a new method of fuel feed which makes for the least disturbanceof the fuel bed and for this reason requires less power than has beenpreviously the case.

My improved stoker is adapted both for mechanical feed of the fuel intothe furnace as well as for hand feed. When applied to mechanical feed,it will be understood that the fuel admitting apparatus will be operatedin synchronism with the stoker mechanism as is usual in the art.

It is to be understood that the principle of my invention may beembodied in other specific mechanism than that shown.

I claim:

l. In combination with a furnace, a stoker comprising a series of gratebars mounted for movement of a nature to feed the fuel through thecombustion area, a common actuating shaft for said bars, automatic meansfor operatively connecting said bars to said shaft in a regular sequenceand means for varying the frequency of actuation of said barsindependently of the frequency of movement of said shaft.

2. In a furnace grate, a series of grate bars disposed beneath thecombustion space of the furnace and adapted to support fuel undergoingcombustion, each of which bars is mounted for a movement of a nature.such as to advance fuel from one end of the furnace to the other, saidbars having a common actuating, oscillatory shaft with linkages betweensaid bars and said shaft adapted to impart said movement to the bars andincluding coupling devices, each comprising a movable key and anelectromagnetic device for moving the key into a slot in said shaft,thereby establishing an operative connection between the linkage and theshaft, and an electric current switching device controlled by said shaftfor actuating said electromagnetic devices and hence the grate bars inpredetermined sequence.

3. The combination recited in claim 2 in which said switching deviceincludes means for manually interrupting said predetermined sequence andfor operating any grate bar out of turn.

4. In a furnace grate, a series of grate bar elements, each of which ismounted for movement of a nature to .advance fuel through a combustionzone, means for moving said elements including a rod connected to eachelement in a manner so as to cause actuation thereof when said rod ismoved back and forth, means for so moving each of said rodsindependently of the others, said means comprising a shaft having amovement of oscillation, means linking each of said rods to said shaftand comprising a coupling device adapted when actuated to lock saidlinking means to said shaft and thereby actuate a particular grate barelement, means for actuating said coupling devices in any desiredsequence and means for varying the frequency of actuation of said barelements independently of the frequency of movement of said shaft.

FRANK Il.` DUMONT.

